func_nav_avoidance_obstacle - Possibly used to give higher priority to go around an area, instead of through it, unless the bots or infected have no other choice. (Used around the cubicles in Dead Air 2)

func_simpleladder - Similar to func_ladder, but uses trigger texture? Three keyvalues names (normal.x, normal.y, normal.z) interfere with the .fgd. (This ladder entity has a team property. It can be found in versus mode. Team = 1 is presumed survivor, team = 2 is infected)